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Gewählte Publikation:

Fernandez-Alonso, MJ; Diaz-Pines, E; Rubio, A.
(2021): Drivers of soil respiration in response to nitrogen addition in a Mediterranean mountain forest
BIOGEOCHEMISTRY. 2021; 155(3): 305-321. FullText FullText_BOKU

Atmospheric nitrogen (N) deposition rates affect soil N dynamics, influencing soil respiration (R-S) rates. However, for the Mediterranean region, the effect of changes in atmospheric N deposition on R-S are not well constrained yet. We investigated the interplay between increased N deposition and tree species composition on R-S at a Scots pine-Pyrenean oak ecotone in Central Spain, and whether the observed responses were mediated by changes on selected soil properties. Throughout 3 years, we simulated two N deposition rates-10 (medium) and 40 kg N ha(-1) a(-1) (high)-over the background deposition (control) in neighbouring stands in which tree species composition (pine or oak) shapes soil stoichiometry and microbial communities. We monitored R-S on a monthly basis during 3 years; in addition, we performed targeted measurements 24 h after the N fertilization events to assess short-term soil responses. During winter and summer, R-S did not respond to enhanced N deposition rates. In spring and autumn, higher R-S rates were observed in the medium-fertilization, but the size and duration of this effect was tree species dependent. We suggest that climate seasonality modulates the response of R-S to N availability, with tree species effects becoming relevant only when environmental conditions are adequate. R-S in fertilized plots was larger from February to May and in September under pine, while under oak a response was observed only in April, probably due to differences in native soil stoichiometry under each tree species. Overall, R-S showed high stability during 3 years of N enrichment in this Mediterranean ecotone area. However, we observed short-term soil responses after N fertilization events-loss of base cations, soil acidification and reduced microbial biomass-which emphasize the need to investigate consequences for the belowground C and N cycles if chronic N enrichment persists in the long run.
Autor*innen der BOKU Wien:
Diaz-Pines Eugenio

Find related publications in this database (Keywords)
Atmospheric nitrogen deposition
Ecotone forests
Soil acidification
Soil microbial biomass
Soil CO2 efflux
Carbon use efficiency

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